Scapho-luno-capitate fusion with proximal lunate articular surface preservation for management of grade IIIA Kienböck's disease: a prospective case series

Abstract

Background: Kienböck's disease is idiopathic lunate avascular necrosis, which may lead to lunate collapse, abnormal carpal motion and wrist arthritis. The current study aimed to assess the outcomes of treating stage IIIA Kienböck's disease by a novel technique of limited carpal fusion via partial lunate excision with preservation of the proximal lunate surface and scapho-luno-capitate (SLC) fusion.

Materials and methods: We conducted a prospective study of patients with grade IIIA Kienböck's disease managed with a novel technique of limited carpal fusion comprising SLC fusion with preservation of the proximal lunate articular cartilage. Autologous iliac crest bone grafting and K-wires fixation were used to enhance the osteosynthesis of the SLC fusion. The minimum follow-up period was 1 year. A visual analog scale (VAS) and the Mayo Wrist Score were utilized for the evaluation of patient residual pain and functional assessment, respectively. A digital Smedley dynamometer was used to measure the grip strength. The modified carpal height ratio (MCHR) was used for monitoring carpal collapse. The radioscaphoid angle, scapholunate angle, and the modified carpal-ulnar distance ratio were used for the assessment of carpal bones alignment and ulnar translocation of carpal bones.

Results: This study included 20 patients with a mean age of 27.9 ± 5.5 years. At the last follow-up, the mean range of flexion/extension range of motion (% of normal side) improved from 52.8 ± 5.4% to 65.7 ± 11.1%, P = 0.002, the mean grip strength (% of normal side) improved from 54.6 ± 11.8% to 88.3 ± 12.4%, P = 0.001, the mean Mayo Wrist Score improved from 41.5 ± 8.2 to 81 ± 9.2, P = 0.002, and the mean VAS score reduced from 6.1 ± 1.6 to 0.6 ± 0.4, P = 0.004. The mean follow-up MCHR improved from 1.46 ± 0.11 to 1.59 ± 0.34, P = 0.112. The mean radioscaphoid angle improved from 63 ± 10º to 49 ± 6º, P = 0.011. The mean scapholunate angle increased from 32 ± 6º to 47 ± 8º, P = 0.004. The mean modified carpal-ulnar distance ratio was preserved and none of the patients developed ulnar translocation of the carpal bones. Radiological union was achieved in all patients.

Conclusions: Scapho-luno-capitate fusion with partial lunate excision and preservation of the proximal lunate surface is a valuable option for treating stage IIIA Kienböck's disease, with satisfactory outcomes. Level of evidence Level IV. Trial registration Not applicable.

Keywords: Iliac crest graft; K-wires; Kienböck’s disease; Limited carpal fusion; Lunate avascular necrosis; Scapho-luno-capitate fusion.

Fig. 1

A Skin incision. B Identification of extensor pollicis longus for incision of the extensor retinaculum of the third extensor compartment. C The contents of the fourth compartment were subperiosteally elevated and retracted ulnarly (green arrow), while the extensor pollicis longus was retracted radially (red arrow). The posterior interosseous nerve (blue arrow) was dissected, 1.5 cm of its length was excised and cauterized, and its proximal end was crushed for posterior wrist denervation. D The wrist capsule was opened in a ligament-splitting fashion with a radially based flap through bisection of the dorsal intercarpal (green arrow) and dorsal radiocarpal ligaments (red arrow). E Bone grafting of the decorticated articular surface of the scaphoid (green arrow), capitate (yellow arrow) and the remaining portion of the proximal lunate (blue arrow)

Fig. 2

A case of a male patient, 33 years old, with grade IIIA Kienböck’s disease treated with partial lunate excision and scapho-luno-capitate fusion. A Preoperative X-rays, anteroposterior and lateral views, showing avascular necrosis and collapse of the lunate. B Preoperative coronal and sagittal CT scans showing collapse of the lunate. C Preoperative MRI showing intact proximal articular cartilage of the lunate. D Immediate postoperative X-rays, anteroposterior and lateral views. E One-year follow-up X-rays, anteroposterior and lateral views, showing complete scapho-luno-capitate fusion